Java Reference
In-Depth Information
Figure 3-7.
Comparing scriptlets, standard actions, and EL
EL Implicit Objects
Scriptlets have access to several JSP implicit objects, as explained in Chapter 2. These objects
allow access to any variables that are held in the particular JSP scopes. EL also provides its own
implicit objects called
EL implicit objects
. EL implicit objects are not the same as JSP implicit objects
(except for
pageContext
). All of these EL Implicit objects are Maps that map the respective scope
attribute names to their values. For instance, using the implicit objects
param
and
paramValues
, it is
possible to access HTTP request parameters. Table
3-3
describes the EL implicit objects.
Table 3-3.
Implicit Objects in EL
Implicit Object
Description
cookie
Map: maps cookie names to a single
Cookie
object.
header
Map: contains the values of each header name
headerValues
Map: maps a header name to a string array of all possible values for the header.
initParam
Map: maps context initialization parameter names to their string parameter values.
param
Map: contains the names of the parameters to a page.
paramValues
Map: maps a parameter nameto a string array of all the values for the parameter.
pageContext
The
PageContext
object.
applicationScope
Map: contains all application-scoped variables.
pageScope
Map: contains all page-scoped variables.
requestScope
Map: contains all request-scoped variables.
sessionScope
Map: contains all session-scoped variables.
